In order to obtain pulps having specified desirable properties from the beating or refining of pulps, it is necessary to control the beating process. In order to obtain such control, so-called freeness testers are generally used to determine the freeness or drainage property of the pulp. To obtain the automatic control of such beating, however, such testers are only used to a small extent, since the freeness does not constitute an unambiquous measurement of the quality and operability of the pulp. The dewatering of the pulp, and thus the measure of its freeness, depends by its very nature on a number of factors, such as the fines and fiber content thereof.